Compensating Adaptive Mixed Criticality Scheduling

The majority of prior academic research into mixed criticality systems assumes that if high-criticality tasks continue to execute beyond the execution time limits at which they would normally finish, then further workload due to low-criticality tasks may be dropped in order to ensure that the high-criticality tasks can still meet their deadlines. Industry, however, takes a different view of the importance of low-criticality tasks, with many practical systems unable to tolerate the abandonment of such tasks. In this paper, we address the challenge of supporting genuinely graceful degradation in mixed criticality systems, thus avoiding the abandonment problem. We explore the Compensating Adaptive Mixed Criticality (C-AMC) scheduling scheme. C-AMC ensures that both high- and low-criticality tasks meet their deadlines in both normal and degraded modes. Under C-AMC, jobs of low-criticality tasks, released in degraded mode, execute imprecise versions that provide essential functionality and outputs of sufficient quality, while also reducing the overall workload. This compensates, at least in part, for the overload due to the abnormal behavior of high-criticality tasks. C-AMC is based on fixed-priority preemptive scheduling and hence provides a viable migration path along which industry can make an evolutionary transition from current practice

Analysis-Runtime Co-design for Adaptive Mixed Criticality Scheduling

In this paper, we use the term “Analysis-Runtime Co-design” to describe the technique of modifying the runtime protocol of a scheduling scheme to closely match the analysis derived for it. Carefully designed modifications to the runtime protocol make the schedulability analysis for the scheme less pessimistic, while the schedulability guarantee afforded to any given application remains intact. Such modifications to the runtime protocol can result in significant benefits with respect to other important metrics. An enhanced runtime protocol is designed for the Adaptive Mixed-Criticality (AMC) scheduling scheme. This protocol retains the same analysis, while ensuring that in the event of high-criticality behavior, the system degrades less often and remains degraded for a shorter time, resulting in far fewer low-criticality jobs that either miss their deadlines or are not executed

Applications in security and evasions in machine learning : a survey

In recent years, machine learning (ML) has become an important part to yield security and privacy in various applications. ML is used to address serious issues such as real-time attack detection, data leakage vulnerability assessments and many more. ML extensively supports the demanding requirements of the current scenario of security and privacy across a range of areas such as real-time decision-making, big data processing, reduced cycle time for learning, cost-efficiency and error-free processing. Therefore, in this paper, we review the state of the art approaches where ML is applicable more effectively to fulfill current real-world requirements in security. We examine different security applications' perspectives where ML models play an essential role and compare, with different possible dimensions, their accuracy results. By analyzing ML algorithms in security application it provides a blueprint for an interdisciplinary research area. Even with the use of current sophisticated technology and tools, attackers can evade the ML models by committing adversarial attacks. Therefore, requirements rise to assess the vulnerability in the ML models to cope up with the adversarial attacks at the time of development. Accordingly, as a supplement to this point, we also analyze the different types of adversarial attacks on the ML models. To give proper visualization of security properties, we have represented the threat model and defense strategies against adversarial attack methods. Moreover, we illustrate the adversarial attacks based on the attackers' knowledge about the model and addressed the point of the model at which possible attacks may be committed. Finally, we also investigate different types of properties of the adversarial attacks

On the limits of probabilistic timing analysis

Over the last years, we are witnessing the steady and rapid growth of Critica! Real-Time Embedded Systems (CRTES) industries, such as automotive and aerospace. Many of the increasingly-complex CRTES' functionalities that are currently implemented with mechanical means are moving towards to an electromechanical implementation controlled by critica! software. This trend results in a two-fold consequence. First, the size and complexity of critical-software increases in every new embedded product. And second, high-performance hardware features like caches are more frequently used in real-time processors. The increase in complexity of CRTES challenges the validation and verification process, a necessary step to certify that the system is safe for deployment. Timing validation and verification includes the computation of the Worst-Case Execution Time (WCET) estimates, which need to be trustworthy and tight. Traditional timing analysis are challenged by the use of complex hardware/software, resulting in low-quality WCET estimates, which tend to add significant pessimism to guarantee estimates' trustworthiness. This calls for new solutions that help tightening WCET estimates in a safe manner. In this Thesis, we investigate the novel Measurement-Based Probabilistic Timing Analysis (MBPTA), which in its original version already shows potential to deliver trustworthy and tight WCETs for tasks running on complex systems. First, we propose a methodology to assess and ensure that ali cache memory layouts, which can significantly impact WCET, have been adequately factored in the WCET estimation process. Second, we provide a solution to achieve simultaneously cache representativeness and full path coverage. This solution provides evidence proving that WCET estimates obtained are valid for ali program execution paths regardless of how code and data are laid out in the cache. Lastly, we analyse and expose the main misconceptions and pitfalls that can prevent a sound application of WCET analysis based on extreme value theory, which is used as part of MBPTA.En los últimos años, se ha podido observar un crecimiento rápido y sostenido de la industria de los sistemas embebidos críticos de tiempo real (abreviado en inglés CRTES}, como por ejemplo la industria aeronáutica o la automovilística. En un futuro cercano, muchas de las funcionalidades complejas que actualmente se están implementando a través de sistemas mecánicos en los CRTES pasarán a ser controladas por software crítico. Esta tendencia tiene dos consecuencias claras. La primera, el tamaño y la complejidad del software se incrementará en cada nuevo producto embebido que se lance al mercado. La segunda, las técnicas hardware destinadas a alto rendimiento (por ejemplo, memorias caché) serán usadas más frecuentemente en los procesadores de tiempo real. El incremento en la complejidad de los CRTES impone un reto en los procesos de validación y verificación de los procesadores, un paso imprescindible para certificar que los sistemas se pueden comercializar de forma segura. La validación y verificación del tiempo de ejecución incluye la estimación del tiempo de ejecución en el peor caso (abreviado en inglés WCET}, que debe ser precisa y certera. Desafortunadamente, los procesos tradicionales para analizar el tiempo de ejecución tienen problemas para analizar las complejas combinaciones entre el software y el hardware, produciendo estimaciones del WCET de mala calidad y conservadoras. Para superar dicha limitación, es necesario que florezcan nuevas técnicas que ayuden a proporcionar WCET más precisos de forma segura y automatizada. En esta Tesis se profundiza en la investigación referente al análisis probabilístico de tiempo de ejecución basado en medidas (abreviado en inglés MBPTA), cuyas primeras implementaciones muestran potencial para obtener un WCET preciso y certero en tareas ejecutadas en sistemas complejos. Primero, se propone una metodología para certificar que todas las distribuciones de la memoria caché, una de las estructuras más complejas de los CRTES, han sido contabilizadas adecuadamente durante el proceso de estimación del WCET. Segundo, se expone una solución para conseguir a la vez representatividad en la memoria caché y cobertura total en caminos críticos del programa. Dicha solución garantiza que la estimación WCET obtenida es válida para todos los caminos de ejecución, independientemente de como el código y los datos se guardan en la memoria caché. Finalmente, se analizan y discuten los mayores malentendidos y obstáculos que pueden prevenir la aplicabilidad del análisis de WCET basado en la teoría de valores extremos, la cual forma parte del MBPTA.Postprint (published version

High-level compiler analysis for OpenMP

Nowadays, applications from dissimilar domains, such as high-performance computing and high-integrity systems, require levels of performance that can only be achieved by means of sophisticated heterogeneous architectures. However, the complex nature of such architectures hinders the production of efficient code at acceptable levels of time and cost. Moreover, the need for exploiting parallelism adds complications of its own (e.g., deadlocks, race conditions,...). In this context, compiler analysis is fundamental for optimizing parallel programs. There is however a trade-off between complexity and profit: low complexity analyses (e.g., reaching definitions) provide information that may be insufficient for many relevant transformations, and complex analyses based on mathematical representations (e.g., polyhedral model) give accurate results at a high computational cost. A range of parallel programming models providing different levels of programmability, performance and portability enable the exploitation of current architectures. However, OpenMP has proved many advantages over its competitors: 1) it delivers levels of performance comparable to highly tunable models such as CUDA and MPI, and better robustness than low level libraries such as Pthreads; 2) the extensions included in the latest specification meet the characteristics of current heterogeneous architectures (i.e., the coupling of a host processor to one or more accelerators, and the capability of expressing fine-grained, both structured and unstructured, and highly-dynamic task parallelism); 3) OpenMP is widely implemented by several chip (e.g., Kalray MPPA, Intel) and compiler (e.g., GNU, Intel) vendors; and 4) although currently the model lacks resiliency and reliability mechanisms, many works, including this thesis, pursue their introduction in the specification. This thesis addresses the study of compiler analysis techniques for OpenMP with two main purposes: 1) enhance the programmability and reliability of OpenMP, and 2) prove OpenMP as a suitable model to exploit parallelism in safety-critical domains. Particularly, the thesis focuses on the tasking model because it offers the flexibility to tackle the parallelization of algorithms with load imbalance, recursiveness and uncountable loop based kernels. Additionally, current works have proved the time-predictability of this model, shortening the distance towards its introduction in safety-critical domains. To enable the analysis of applications using the OpenMP tasking model, the first contribution of this thesis is the extension of a set of classic compiler techniques with support for OpenMP. As a basis for including reliability mechanisms, the second contribution consists of the development of a series of algorithms to statically detect situations involving OpenMP tasks, which may lead to a loss of performance, non-deterministic results or run-time failures. A well-known problem of parallel processing related to compilers is the static scheduling of a program represented by a directed graph. Although the literature is extensive in static scheduling techniques, the work related to the generation of the task graph at compile-time is very scant. Compilers are limited by the knowledge they can extract, which depends on the application and the programming model. The third contribution of this thesis is the generation of a predicated task dependency graph for OpenMP that can be interpreted by the runtime in such a way that the cost of solving dependences is reduced to the minimum. With the previous contributions as a basis for determining the functional safety of OpenMP, the final contribution of this thesis is the adaptation of OpenMP to the safety-critical domain considering two directions: 1) indicating how OpenMP can be safely used in such a domain, and 2) integrating OpenMP into Ada, a language widely used in the safety-critical domain.Actualment, aplicacions de dominis diversos com la computació d'altes prestacions i els sistemes d'alta integritat, requereixen nivells de rendiment assolibles només mitjançant arquitectures heterogènies sofisticades. No obstant, la natura complexa d'aquestes dificulta la producció de codi eficient en un temps i cost acceptables. A més, la necessitat d’explotar paral·lelisme introdueix complicacions en sí mateixa (p. ex. bloqueig mutu, condicions de carrera,...). En aquest context, l'anàlisi de compiladors és fonamental per optimitzar programes paral·lels. Existeix però un equilibri entre complexitat i beneficis: la informació obtinguda amb anàlisis simples (p. ex. definicions abastables) pot ser insuficient per moltes transformacions rellevants, i anàlisis complexos basats en models matemàtics (p. ex. model polièdric) faciliten resultats acurats a un alt cost computacional. Existeixen molts models de programació paral·lela que proporcionen diferents nivells de programabilitat, rendiment i portabilitat per l'explotació de les arquitectures actuals. En aquest marc, OpenMP ha demostrat molts avantatges respecte dels seus competidors: 1) el seu nivell de rendiment és comparable a models molt ajustables com CUDA i MPI, i proporciona més robustesa que llibreries de baix nivell com Pthreads; 2) les extensions que inclou la darrera especificació satisfan les característiques de les actuals arquitectures heterogènies (és a dir, l’acoblament d’un processador principal i un o més acceleradors, i la capacitat d'expressar paral·lelisme de tasques de gra fi, ja sigui estructurat o sense estructura; 3) OpenMP és àmpliament implementat per venedors de xips (p. ex. Kalray MPPA, Intel) i compiladors (p. ex. GNU, Intel); i 4) tot i que el model actual manca de mecanismes de resiliència i fiabilitat, molts treballs, incloent aquesta tesi, busquen la seva introducció a l'especificació. Aquesta tesi adreça l'estudi de tècniques d’anàlisi de compiladors amb dos objectius: 1) millorar la programabilitat i la fiabilitat de OpenMP, i 2) provar que OpenMP és un model adequat per explotar paral·lelisme en sistemes crítics. En particular, la tesi es centra en el model de tasques per què aquest ofereix la flexibilitat per abordar aplicacions amb problemes de balanceig de càrrega, recursivitat i bucles incomptables. A més, treballs recents han provat la predictibilitat en qüestió de temps del model, escurçant la distància cap a la seva introducció en sistemes crítics. Per a poder analitzar aplicacions que utilitzen el model de tasques d’OpenMP, la primera contribució d’aquesta tesi consisteix en l’extensió d'un conjunt de tècniques clàssiques de compilació per suportar OpenMP. Com a base per incloure mecanismes de fiabilitat, la segona contribució consisteix en el desenvolupament duna sèrie d'algorismes per detectar de forma estàtica situacions que involucren tasques d’OpenMP, i que poden conduir a una pèrdua de rendiment, resultats no deterministes, o fallades en temps d’execució. Un problema ben conegut del processament paral·lel relacionat amb els compiladors és la planificació estàtica d’un programa representat mitjançant un graf dirigit. Tot i que la literatura sobre planificació estàtica és extensa, aquella relacionada amb la generació del graf en temps de compilació és molt escassa. Els compiladors estan limitats pel coneixement que poden extreure, que depèn de l’aplicació i del model de programació. La tercera contribució de la tesi és la generació d’un graf de dependències enriquit que pot ser interpretat pel sistema en temps d’execució de manera que el cost de resoldre les dependències sigui mínim. Amb les anteriors contribucions com a base per a determinar la seguretat funcional de OpenMP, la darrera contribució de la tesi consisteix en adaptar OpenMP a sistemes crítics, explorant dues direccions: 1) indicar com OpenMP es pot utilitzar de forma segura en un domini com, i 2) integrar OpenMP en Ada, un llenguatge molt utilitzat en el domini de seguretat.Postprint (published version

CLARIN. The infrastructure for language resources

CLARIN, the "Common Language Resources and Technology Infrastructure", has established itself as a major player in the field of research infrastructures for the humanities. This volume provides a comprehensive overview of the organization, its members, its goals and its functioning, as well as of the tools and resources hosted by the infrastructure. The many contributors representing various fields, from computer science to law to psychology, analyse a wide range of topics, such as the technology behind the CLARIN infrastructure, the use of CLARIN resources in diverse research projects, the achievements of selected national CLARIN consortia, and the challenges that CLARIN has faced and will face in the future. The book will be published in 2022, 10 years after the establishment of CLARIN as a European Research Infrastructure Consortium by the European Commission (Decision 2012/136/EU)

CLARIN

The book provides a comprehensive overview of the Common Language Resources and Technology Infrastructure – CLARIN – for the humanities. It covers a broad range of CLARIN language resources and services, its underlying technological infrastructure, the achievements of national consortia, and challenges that CLARIN will tackle in the future. The book is published 10 years after establishing CLARIN as an Europ. Research Infrastructure Consortium

Critical Services continuity, Resilience and Security: Proceedings of the 56th ESReDA Seminar

Critical Infrastructures (CIs) remain among the most important and vital service providers to modern societies. Severe CIs’ disruptions may endanger security of the citizen, availability of strategic assets and even the governance stability. Not surprisingly, CIs are often targets of intentional attacks, either of physical or cyber nature. Newly emerging hybrid threats primarily target CIs as part of the warfare. ESReDA as one of the most active EU networks in the field has initiated a project group (CI-PR/MS&A-Data) on the “Critical Infrastructure/Modelling, Simulation and Analysis – Data”. The main focus of the project group is to report on the state of progress in MS&A of the CIs preparedness & resilience with a specific focus on the corresponding data availability and relevance. In order to report on the most recent developments in the field of the CIs preparedness & resilience MS&A and the availability of the relevant data, ESReDA held its 48th, 52nd and 56th Seminars. The 56th ESReDA Seminar on “Critical Services continuity, Resilience and Security” attracted about 30 participants from industry, authorities, operators, research centres and academia. The seminar programme consisted of 18 technical papers, two plenary speeches and an interactive session on Climate & CI protection.JRC.G.10-Knowledge for Nuclear Security and Safet

CLARIN

The book provides a comprehensive overview of the Common Language Resources and Technology Infrastructure – CLARIN – for the humanities. It covers a broad range of CLARIN language resources and services, its underlying technological infrastructure, the achievements of national consortia, and challenges that CLARIN will tackle in the future. The book is published 10 years after establishing CLARIN as an Europ. Research Infrastructure Consortium